Our invention relates to electronic musical instruments in general and, in particular, to a polyphonic electronic musical instrument of the type having a plurality of sounding channels for simultaneous production of tones corresponding to notes played on one or more keyboards, as well as notes established (created) automatically in predetermined relationship to the played notes. Still more particularly, our invention concerns such an instrument with facilities for controlling the channeling operation of notes to be sounded, depending upon whether the notes are played ones or automatically established ones.
The electronic musical instrument has been known and used extensively which, in response to the depression of keys on a keyboard or keyboards, generates binary-coded key data representative of the played notes (depressed keys) and which also automatically produces data indicative of unplayed notes having a certain musically acceptable relationship with the played notes, being automatically established as based on the played notes according to the predetermined conditions. We will call the first type of data the "primary key data" (meaning played key data), and the second type of data the "secondary key data" (meaning supplementary key data), to facilitate the subsequent description. The known instrument includes a data memory having several storage channels each for storing one of the generated sets of primary and secondary key data, prior to delivery to a multichannel tone generator circuit for translation into corresponding tones.
A problem arises in this type of instrument from the fact that the storage channels of the data memory are usually considerably less in number than the keys of the instrument. Should a set of primary or secondary key data be generated when all the storge channels are occupied, either of the data sets in storage must be canceled or invalidated. In such cases it is desirable that a set of secondary, rather than primary, key data be canceled to empty one of the storage channels for the reception of the new data set. Such preferential cancellation of secondary key data has not been possible heretofore. This is because, once the key data have been assigned to the storage channels of the data memory, the conventional instrument has not been equipped to distinguish between the primary and the secondary key data.
In order to better illustrate the above problem, there may be considered an electronic musical instrument which generates, as the secondary key data, those representative of notes having a predetermined octaval relation with notes played on the upper keyboard, and/or of notes that are of the same names as those played on the lower keyboard but which are more intimately associated octavally with notes played on the upper keyboard. Such secondary key data are stored in the data memory along with primary key data representative of notes played on the upper keyboard. Subsequently processed into tone signals by the tone generator circuit, the primary and secondary key data are sounded together via an audio output system.
Let it be assumed that, in the instrument of this type, the performer has depressed a key on the upper keyboard when all the storage channels of the data memory are filled with the primary and secondary key data. As will be apparent from the foregoing, the notes represented by the secondary key data are of an accessory (supplementary) character with respect to the notes played on the upper keyboard. Thus, in emptying one of the storage channels for the newly generated set of primary key data, a set of secondary, rather than primary, key data in storage should be canceled to cut short the production of the corresponding tone. The attainment of this objective calls for the provision of means for discriminating whether the data set on each channel of the data memory is primary or secondary.